The present invention relates generally to a system for recharging plug-in hybrid vehicles and more particularly to a system that balances the electrical power demands on local distribution networks.
Due to rising cost of petroleum and the fuels derived from it, the desire to improve efficiency to reduce air pollutants and increasingly more restrictive regulatory requirements, the automotive industry has developed new types of vehicles that utilize a combination of power sources to provide the necessary energy to provide propulsion for the vehicle. Rather than rely solely on an internal combustion engine, these new vehicles, referred to as hybrid vehicles, utilize an internal combustion engine in combination with an electric motor. Another version called a plug-in hybrid may also supplement the charging of the batteries from the electric grid or other sources. Depending on the mode of operation, the vehicle will use the combustion engine, the electric motor, or a combination thereof. By using the electric motor at various times, the combustion engine could be shut off, reducing the amount of gasoline or other fuel consumed using electricity to power the motor instead. The electric motor is powered by batteries that are periodically recharged through a combination of a generator coupled to the combustion engine, regenerative breaking technology and from the local utility grid or other external source of electricity. Regenerative breaking allows the capture of energy that would otherwise be dissipated through heat when the vehicle is slowed down or brought to a stop.
Hybrid vehicles provided many advantages over previously introduced all electric vehicles. The hybrid vehicle provided greater range and more flexibility for the operator. Since the all-electric vehicle needed to be charged periodically, and required several hours at a minimum to recharge, the operator needed to remain aware of the level of charge remaining in the batteries to ensure they were able to return to their charging station. Hybrid vehicles, in contrast, by having two different sources of propulsion do not carry the same risks due to the wide availability of fuels such as gasoline.
A typical hybrid vehicle uses a nickel metal hydride battery to store electrical charge. When run in pure electric mode, the hybrid vehicle can only operate for short distances, 2 km-32 km for example, before requiring the use of the gasoline engine. Since the gasoline engine recharges the batteries, at least in part, the vehicle manufacturers need to balance the amount of battery storage against fuel efficiency to provide a vehicle that meets the consumers performance expectations.
To further lower emissions and increase gas mileage, some manufacturers have developed so-called “plug-in” hybrid (“PIH”) vehicles. The PIH vehicles include a receptacle that connects the batteries to a standard 110V or 220V household electrical outlet and allows the consumer to recharge the batteries using utility electric power rather than by burning gasoline or other fuel in a combustion engine. This allows the PIH vehicles to have a longer range in electric mode of operation since larger capacity batteries may be used, resulting in vehicle that uses less gasoline and thus lower emissions. While the PIH vehicle does place additional demands on the existing utility electrical distribution.
While existing electrical distribution systems are suitable for this new purpose, there remains a need for improvements, particularly regarding the control of recharging of PIH vehicles and the increased efficiencies that may be gained from existing utility electrical distribution networks.